全文获取类型
收费全文 | 1342篇 |
免费 | 20篇 |
国内免费 | 16篇 |
专业分类
化学 | 828篇 |
晶体学 | 9篇 |
力学 | 50篇 |
数学 | 195篇 |
物理学 | 296篇 |
出版年
2022年 | 9篇 |
2021年 | 15篇 |
2020年 | 14篇 |
2017年 | 10篇 |
2016年 | 20篇 |
2015年 | 16篇 |
2014年 | 16篇 |
2013年 | 67篇 |
2012年 | 35篇 |
2011年 | 66篇 |
2010年 | 45篇 |
2009年 | 31篇 |
2008年 | 43篇 |
2007年 | 63篇 |
2006年 | 48篇 |
2005年 | 53篇 |
2004年 | 48篇 |
2003年 | 38篇 |
2002年 | 45篇 |
2001年 | 34篇 |
2000年 | 35篇 |
1999年 | 36篇 |
1998年 | 12篇 |
1997年 | 20篇 |
1996年 | 32篇 |
1995年 | 20篇 |
1994年 | 18篇 |
1993年 | 32篇 |
1992年 | 12篇 |
1991年 | 21篇 |
1990年 | 26篇 |
1989年 | 20篇 |
1988年 | 17篇 |
1987年 | 21篇 |
1986年 | 18篇 |
1985年 | 25篇 |
1984年 | 29篇 |
1983年 | 17篇 |
1982年 | 16篇 |
1981年 | 19篇 |
1980年 | 18篇 |
1979年 | 20篇 |
1978年 | 11篇 |
1977年 | 12篇 |
1976年 | 13篇 |
1975年 | 14篇 |
1974年 | 10篇 |
1973年 | 12篇 |
1972年 | 12篇 |
1968年 | 9篇 |
排序方式: 共有1378条查询结果,搜索用时 140 毫秒
161.
162.
163.
164.
Optimization of the pore sizes of various silica gels used as supports in the immobilization of 8-quinolinol is described. Increased capacity is observed as pore size decrease to the opt? at about 6 nm. At smaller pore sizes, steric effects appear to predominate, ? capacities decrease sharply. An explanation for these effects is proposed, it was confirmed by using molecular models. 相似文献
165.
Albert W. Marshall 《Stochastic Processes and their Applications》1975,3(3):293-300
For random variables T1,…,Tn, the gradient of is called the hazard gradient. Some properties of this multivariate version of the hazard rate are demonstrated, and some examples are given to show the usefulness of the hazard gradient in characterizing distributions or families of distributions. 相似文献
166.
167.
Consider the relaxation of an integer programming (IP) problem in which the feasible region is replaced by the intersection of the linear programming (LP) feasible region and the corner polyhedron for a particular LP basis. Recently a primal-dual ascent algorithm has been given for solving this relaxation. Given an optimal solution of this relaxation, we state criteria for selecting a new LP basis for which the associated relaxation is stronger. These criteria may be successively applied to obtain either an optimal IP solution or a lower bound on the cost of such a solution. Conditions are given for equality of the convex hull of feasible IP solutions and the intersection of all corner polyhedra. 相似文献
168.
169.
The microstructure and transport properties of various 90° grain boundaries in (103) oriented YBa2Cu3O7(YBCO) thin films grown epitaxially in situ by 90° off-axis sputtering are compared. The (103) films grown on (101) LaAlO3 and (101) SrTiO3 substrates have specific sets of 90° grain boundaries in both principal in-plane directions: 90° [010] twist boundaries along the [101] direction, and 90° [010] symmetrical tilt boundaries and 90° [010] basal-plane-faced tilt boundaries along the (301) direction. No weak-link behavior is observed across some of these boundaries by transport critical current density and normalized magnetic field dependence of J
c measurements along both those in-plane directions. High-resolution transmission electron microscopy reveals variations in the structure and microfaceting of the 90° boundaries, which may contribute to the absence of weak-link behavior. These results have important implications for understanding the behavior of step-edge Josephson junctions. 相似文献
170.